Complications Associated with Embolization of Skull Base Tumors and How To Avoid Them

Introduction: Treatment of skull base tumors, especially those of larger extent, requires interdisciplinary management including neurosurgery, ENT surgery, facial maxillary surgery, and radiation therapy. For treatment decisions, an optimized diagnostic work-flow helps to select patients suitable for different treatment options and to decide whether a single or combined approach is necessary. In addition to the clinical data, mainly neuroradiological imaging (both CT and MRI) assists decision-making by showing the location, extent, vicinity to cranial nerves and larger vessels, as well as the tumor vascularization.

Embolizations are mainly applied in meningiomas, paragangliomas (glomus tympanicojugulare tumors), juvenile angioblastomas, and (seldom) carcinomas and bone metastases.

Methods: Before embolization, a thorough analysis of the complete angioarchitecture of the tumor vessels, the feeding arteries, especially of collaterals and the draining type is mandatory. Especially collaterals from the periorbital region and the middle cranial fossa to the internal carotid artery, as well as anastomoses between the posterior branches of the external carotid artery to the vertebral artery, grouped under the term “dangerous vessels,” have to be identified before injection of embolic material. Moreover, one must be aware that collaterals can open even after partial embolization, which requires a permanent angiographic control in several steps during embolization.

Results: To avoid false embolization into nontumorous vessels all those anatomical details must be considered to find the right superselective position of the catheter, since proximal locations have a higher risk of existing collaterals. In addition, complications of ischemic lesions can arise due to swelling of the tumor after embolization, which can be treated by steroids or by early operation after embolization. Seldom, bleeding into the tumor or in the surrounding area can occur in the early phase after embolization when a liquid embolic agent causes an obstruction of the venous drainage.

Conclusions: (1) To reduce the vascularization of tumors in order to minimize blood loss during surgery; (2) to shrink large tumors for better surgical approach and to achieve more space for surgical manipulation; (3) to shrink tumors close to cranial nerves in order to separate the tumor from the nerval structures and to avoid violation of the nerves during tumor resection; (4) to achieve tumor control or tumor shrinkage in nontreatable patients (medical reasons, aged, not achievable by surgery, not suitable for radiation); (5) to avoid complications by embolization a detailed anatomical analysis based on neuroimaging is a prerequisite.